Extract a DelegateInventory from EnderChestInventory

src/block/inventory/EnderChestInventory.php

@@ -24,12 +24,9 @@ declare(strict_types=1);
 namespace pocketmine\block\inventory;
 
 use pocketmine\block\tile\EnderChest;
-use pocketmine\inventory\BaseInventory;
-use pocketmine\inventory\CallbackInventoryListener;
+use pocketmine\inventory\DelegateInventory;
 use pocketmine\inventory\Inventory;
-use pocketmine\inventory\InventoryListener;
 use pocketmine\inventory\PlayerEnderInventory;
-use pocketmine\item\Item;
 use pocketmine\network\mcpe\protocol\BlockEventPacket;
 use pocketmine\player\Player;
 use pocketmine\world\Position;
@@ -40,52 +37,23 @@ use pocketmine\world\sound\Sound;
 /**
  * EnderChestInventory is not a real inventory; it's just a gateway to the player's ender inventory.
  */
-class EnderChestInventory extends BaseInventory implements BlockInventory{
+class EnderChestInventory extends DelegateInventory implements BlockInventory{
 	use AnimatedBlockInventoryTrait {
 		onClose as animatedBlockInventoryTrait_onClose;
 	}
 
 	private PlayerEnderInventory $inventory;
-	private InventoryListener $inventoryListener;
 
 	public function __construct(Position $holder, PlayerEnderInventory $inventory){
-		parent::__construct();
+		parent::__construct($inventory);
 		$this->holder = $holder;
 		$this->inventory = $inventory;
-		$this->inventory->getListeners()->add($this->inventoryListener = new CallbackInventoryListener(
-			function(Inventory $unused, int $slot, Item $oldItem) : void{
-				$this->onSlotChange($slot, $oldItem);
-			},
-			function(Inventory $unused, array $oldContents) : void{
-				$this->onContentChange($oldContents);
-			}
-		));
 	}
 
 	public function getEnderInventory() : PlayerEnderInventory{
 		return $this->inventory;
 	}
 
-	public function getSize() : int{
-		return $this->inventory->getSize();
-	}
-
-	public function getItem(int $index) : Item{
-		return $this->inventory->getItem($index);
-	}
-
-	protected function internalSetItem(int $index, Item $item) : void{
-		$this->inventory->setItem($index, $item);
-	}
-
-	public function getContents(bool $includeEmpty = false) : array{
-		return $this->inventory->getContents($includeEmpty);
-	}
-
-	protected function internalSetContents(array $items) : void{
-		$this->inventory->setContents($items);
-	}
-
 	public function getViewerCount() : int{
 		$enderChest = $this->getHolder()->getWorld()->getTile($this->getHolder());
 		if(!$enderChest instanceof EnderChest){
@@ -115,9 +83,5 @@ class EnderChestInventory extends BaseInventory implements BlockInventory{
 		if($enderChest instanceof EnderChest){
 			$enderChest->setViewerCount($enderChest->getViewerCount() - 1);
 		}
-		if($who === $this->inventory->getHolder()){
-			$this->inventory->getListeners()->remove($this->inventoryListener);
-			$this->inventoryListener = CallbackInventoryListener::onAnyChange(static function() : void{}); //break cyclic reference
-		}
 	}
 }

src/inventory/DelegateInventory.php

@@ -0,0 +1,78 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\inventory;
+
+use pocketmine\item\Item;
+use pocketmine\player\Player;
+use function count;
+
+/**
+ * An inventory which is backed by another inventory, and acts as a proxy to that inventory.
+ */
+class DelegateInventory extends BaseInventory{
+
+	private Inventory $backingInventory;
+	private InventoryListener $inventoryListener;
+
+	public function __construct(Inventory $backingInventory){
+		parent::__construct();
+		$this->backingInventory = $backingInventory;
+		$this->backingInventory->getListeners()->add($this->inventoryListener = new CallbackInventoryListener(
+			function(Inventory $unused, int $slot, Item $oldItem) : void{
+				$this->onSlotChange($slot, $oldItem);
+			},
+			function(Inventory $unused, array $oldContents) : void{
+				$this->onContentChange($oldContents);
+			}
+		));
+	}
+
+	public function getSize() : int{
+		return $this->backingInventory->getSize();
+	}
+
+	public function getItem(int $index) : Item{
+		return $this->backingInventory->getItem($index);
+	}
+
+	protected function internalSetItem(int $index, Item $item) : void{
+		$this->backingInventory->setItem($index, $item);
+	}
+
+	public function getContents(bool $includeEmpty = false) : array{
+		return $this->backingInventory->getContents($includeEmpty);
+	}
+
+	protected function internalSetContents(array $items) : void{
+		$this->backingInventory->setContents($items);
+	}
+
+	public function onClose(Player $who) : void{
+		parent::onClose($who);
+		if(count($this->getViewers()) === 0 && count($this->getListeners()->toArray()) === 1){
+			$this->backingInventory->getListeners()->remove($this->inventoryListener);
+			$this->inventoryListener = CallbackInventoryListener::onAnyChange(static function() : void{}); //break cyclic reference
+		}
+	}
+}